Question

What is the most commonly used overlay?

• A. Flexible over rigid
• B. Rigid over flexible
• C. Flexible over flexible
• D. Rigid over rigid

Hint:

The prevalence of flexible pavements (asphalt) in road networks makes flexible-over-flexible overlays the most common type of rehabilitation. Key considerations for overlays include preventing reflection cracking, ensuring proper bonding, and maintaining drainage.

Answer 1

The Correct Option is C

In civil engineering, particularly in the context of road construction and maintenance, overlays are critical in extending the life and improving the performance of pavements. An overlay is a layer of material applied to an existing road surface to restore its smoothness and structural capacity.

The options for overlays are:

• Flexible over rigid
• Rigid over flexible
• Flexible over flexible
• Rigid over rigid

The most commonly used overlay is flexible over flexible. This approach involves laying a new layer of asphalt (flexible) over the existing asphalt pavement (also flexible).

Explanation:

• Flexible overlays are typically made of asphalt. They are cost-effective, easier to apply, require less time for installation, and can be applied to roads with minor surface issues that do not have deep structural problems.
• Rigid overlays, made of concrete, are more suitable for heavily loaded environments but are more expensive and require longer curing times.

Applying a flexible overlay over an existing flexible pavement is often chosen because it can improve minor surface irregularities, enhance skid resistance, and provide additional waterproofing to protect the underlying layers without the need for complex structural modifications.